Mud weighing device



Och 4 J. R. PETTIGROVE 2,360,977

MUD WEIGHING DEVICE I Filed June 22, 1942 2 Sheets-Sheet 1 lNV NTOR JOHNR. PETTIGROVE v 'ITOR EYS J. R. PETTIGRQVE MUD wmefime DEVICE Filed June22, 1942 2 Sheets-Sheet 2 IN JOHN R. PETTIGROVE VENTOR Patented Oct. 24,1944 MUD wnrcrrmc nnvrcn John R. Pettigrove, League City, Tex., assignorto Phillips Petroleum Company, a corporation of Delaware ApplicationJune 22, 1942, Serial No. 447,994

' 4 Claims.

My invention relates to automatic means for detgrmining and recordingthe density of drilling mu More specifically, my invention is asimplified apparatus which automatically admits a sample of the mud,determines and records the weight per gallon, disposes of the sample andwashes the .apparatus before admitting a subsequent sample.

All of these functions are performed or controlled by the weight of themud itself. The only source of energy employed, other than gravity; isthe -spring-driven clock mechanism used in conjunction with therecording chart. Thus my invention is obviously cheaper and simpler ofconstruction and maintenance than are the complicated motordriven orpower controlled arrangements which.

have heretofore been devised.

The primary object of my invention lies in the provision of a relativelycheap and simple density recorder for drilling mud.

It is a further object to provide a recording densitometer for drillingmud which is automatically self-cleaning.

It is also an object to provide a device of the class described whichhas a minimum of moving or wearing parts exposed to the drilling mud,thereby insuring reliability and longevity of the instrument.

It is a, further object to provide a device which is well adapted toconstruction from lightweight Below the open end of spout is suspended ahopper tank 2i, the suspension consisting of a pivoted beam 22 and asupport rod 22 attached thereto. The beam 22 is pivotally mounted to thebearing support is by a pin 24.

The hopper tank 2i is provided with a bottom opening 25 and foot-valve28, the latter simply a fiat disc or plate'to the center of which isattached a downwardly extending stem 21. The stem 21 is preferablythreaded in valve plate 28, so that ad-' justment of the protruding stemlength may be had." A locknut'28 is provided for retaining the desiredadjustment. A slidabie counterweight 29 is provided on beam 22, with aset-screw 30 for locking thesame at any desired location. ,An additionalsmall opening iii is provided in the bottom oi tank 2i.

A conduit Si is located directly over the opening it in tank i0, havinga downwardly-extending branch portion 82, the lower (open) end of whichis substantially below the level of the mouth 33 of spout 20. By meansof a rod 34 and yoke-piece 35 a valve member 88 is suspended below theend of conduit 32. The valve member 36 has-a conical portion 31adaptedto seat in the open end of conduit 32 when in contact therewith.Fig. 2

metal or even from wooden parts, so that emergency repairs may be madein the field if necessary. m In the drawings forming part of thisspecificaon,

Fig.1 is an, elevational view of in section, and

my device, partly Fig. 2 is a fragmentary side view of'part of ilnyinvention which is shown in sectionin Fig.

, 8- 3 is an-enlarged sectional view ofan element shown in Fig. ,1.

Referringnow particularly to, Fig. 1, the numeral it refers generally toa displacement tank. An inserted bottom ii is located at some distanceopen-bottomed base portion i3, which has cutaway portions and leg-likeportions 15. The bottom ii is of asymmetric'frustro-conical form, havingan opening IS in the horizontally disposed lowest portion ii. The top ofthe tank is open 'except for a small elevated portion It at one side.

which is provided to carry a bearing support ll. An overflow spout 20 isprovided in the tank wall as shown. I

- open, The end 46 is disposed over the open top] from the bottom ofwalls l2, thus forming an known. The top 48 of the tank is of conicalform.

and is attached to a suspending rod 49. During I shows a fragmentaryside view which is helpful to give a clear understanding of thisstructure.

Depending from valve 38 is a stem 38, to which is secured a fiat, dischaving a tapered-guiding piece 40. The disc 39 has a projected area Mappreciabie magnitude, for reasons to be explained later. The guide piece40 is small in cross section as compared with opening I8, its solefunction being to assure overlapping or registry of disc 39 over openingll.

A conduit for clean water passes below any convenient point on beam 22,where a valve 42 is installed. This valve will be described in detailelsewhere in this specification. A continuing conduit 43 leads over oraround thetank iii in any convenient manner, terminating in a branch ordistributing portion 44, both ends of which are of hopper tank 2i; theright-hand branch passes through the wall of tank iii as shown andterminates at a point above the flotation member 41.

The flotation member 41 above referred .toco'nstitutes the densitymeasuring element of my =de.- I

vice. The element consists of avcompietely enclosed tank whose volume ordisplacement is accurately the fabrication of the tank, molten lead orother suitable weighting material is poured into the 'the element 41.

bottom as at it.v The total weight 01' the element 41 including weightit must exceed the weight or an equal volume oi the most dense medium tobe measured. Stated another way, the density or the weighted element 41must exceed the maximum density which is contemplated to be determined.For the purposes herein set forth, I find it convenient to use a volumeof exactly one gallon and a total weight of approximately 20 pounds forEnclosed in a suitable case BI is a clock-driven recorder includinga'chart 52 and a pen-arm 53.-

While any conventional recorder may be used, I I

belt-type chart which is wound between a pair of driven spools. Circularrotating charts may bev used, but are not as convenient since theyrequire a periodic and prompt replacement at the end of prefer to use arecorder having a rectilinear or each 360 of rotation. The housing 5| issup ported above tank It by means oi suitable supports 54.

The support rod 49 passes through suitable apertures I! and It in thewalls of tank It and housing II, respectively. A tension spring 51 isattached securely to the top or housing 8| and its lower end is securedto rod 42. The spring 51 is so designed that it will bear the iullunbuoyed weight 01' member 41 without undue stress, and at the-same timewill have sumcient resiliency to be sensitive to small increments otloadthereon. By means or a collar 58, lever 89 and a light tensionhair-spring O0, pen-arm 52 is operativelyengaged with rod 4.. Roughadjustment oi the pen-arm is provided by the collar II and its lock-,

ing screw I, by manipulation of which the collar may be shiited on rod49 to bring the penarm It to an origin or reference line on the chart 52for calibrating purposes. For finer adiustment, the use oi. avernier-typeD -arm such as is provided on conventional recordingpressure gauges is recommended. This type oi! arm is well known in theinstrument art and need not be shown orv explained in detail here.

In Fig. 3 is shown the details of valve 42, previously referred to. Thisvalve has a 'r-iorm body 2, provided with an inlet 82 and outlet 64,suitably threaded for attachment to iron pipe or other conduit as may bedesired. The interior or the valve is divided into chambers BI and I.

by the separating wall 01. A valve port 22 is provided in wall 61. theport beingchamiered slightly and ground smooth on its upper side. Asolid metal valve member I is provided in chamber 10, having a taperedportion 1| adapted to seat raised to thc uppermost limit.

, Referring again now to Fig. 1, it is seen that a wire or small rod 10operatively connects beam 220! my device to the stem 14 ct valve 42. Therod 10 is looped at its lower end, the rod being bent at right angles ata point 11 so as to place the looped portion II in a horizontal plane,The stem 14 passes through the loop, and at a point above the same isprovided a collar II with a setscrew ll. Thus upward travel or rod 18will, upon contact of loop 18 with collar 12, cause of rod 12 with stem14 is such that motion 01' rod 12 (and therefore of weight 29) in adownward direction can continue after the valve 42 has reached theclosed condition. It is seen then that valve 42 is closed only by weightof the valve member 88 and rod 14.

In operation. the conduit 2| is placed in communication with a part 0!the system through which the drilling mud is constantly circulated. Atthe beginning of a cycle of operation oi'my device, tanks l0 and 2| areempty; valves 28, 29 and 42 are closed; valve 31 is open, and a part 01thelmud travelling through line 3| begins to enter tank ll via theconduit branch 32. Tank ||I eventually fills to the level determined bythe opening 38 0! overflow spout 20, flotation member 41 (which is ofgreater density than the mud) consequently becomes completely submergedin the fluid mud. As the mud rises around member 41, the member beginsto be buoyed up by the displaced mud, with the result that the downwardload on spring 51 gradually decreases and member 41 consequently rises.The rise of member 41 during filling of tank l0 causes the recording pento trace the curve AB on the chart.

When the mud reaches the level or opening 22, mud begins to now throughspout 20 into tank 2|. Note that, beiore tank 2| begins to fill theprincipal loads to the right of the pivot on beam 22 are two in number,namely; (1)

the counter-weight 28, and (2) the static head of fluid in tank Inacting on the exposed top surface of valve disc 29. when the filling oftank 2| attached to valve member I ing iull closure. or the variousvalves.

proceeds to the point where the filled weight is sumcient to overcomethe combined eflect oi the two loads above noted, the force systembecomes overbalanced so as to begin op ning of the bottom outlet II intank "I. As soon as this opening begins, the efiect oi the static headof mud above disc 2. becomes equalized, and the weight 2! now becomesthe only ractor in opposition to the weight oi tank 2| and its contents.This sudden reduction or clockwise movement producing force results insudden dropping of tank 2|. The results are: .(1) closure of duct 32 byseat 31; (2) full opening oi bottom valve 39- in tank 10; (3) opening ofvalve 28 in tank 2| upon contact of stem 21 with the drilling derrickfloor or other supporting surface, and (4) opening of water valve 42. sa

. The sizes of openings i6 and 25 are so proportioned that tank indrains completely in the time required to drain from tank 2| a weight ofmud equal to the initial weight imposed on disc 39 by the static head ofmud in tank iii. Thus, by proper selection of sizes of openings it and25, time may be provided for complete draining or mud from tank It andfor thorough flushing or member 41 with clean water from inlet 48 beforebeam 22 again reaches a balanced condition.

Water meanwhile is introduced to tank 2| i'rom outlet 45, diluting themud and promoting its complete removal.

when beam 22 again slightly overbalances in the clockwise direction,valves 26,18 and 42 begin to re-close and valve It begins to open. Aftervalve 20 becomes completely closed, diluted mud or clear water,whichever remains in tank 2|. continues to drain through opening 8|,permitting further unbalancing of beam 22 and insur- Draining of tank 2|is completed through opening 8| during re-fllling of tank ID in thesubsequent cycle 01' operation.

- valve 42 to be opened. The sliding engagement to As was noted before,the curve A- B will be traced on chart 62 during the submersion by Assoon as eleincoming mud or element 41. ment 41 becomes completelysubmerged buoyant equilibrium in accordance with Archimedes principle'isreached and no further substantial movement of the recording 'pen willoccur until the recording the density of well-drilling mud, it alsocould be used to advantage in any application wherea continuousmeasurement of density of fluid or semifluid materials is desired.

tank It has drained sufliciently to begin. uncovering of element 41.Hence, in the interim, the recording pen will trace the substantiallystraight curve .segment B-C. When element 41 begins be read directly aspounds per gallon (the customary units for this work) or in any otherterms that may be desired. I

It will be noted that provision is madefor ad- 4 Justment of the time ofopening of all the valves employed in my device, so-that the propersequence and interval of operation may be secured.

It is or course obvious that many modifications may be made in theconstruction of the various valves. In this connection, I will point outthe principal considerations with regard to the type 83:1 design of thevalves which'I have found suita e.

The water valve 42 as illustrated isa desirable type tor the reason thatlittle energy is required to open it, and it is self-closing. Since theweight of the valvememberitself is relied upon to close the port, theweight of the valve member must exceed the product of the water pressuretimes the port area. In order to hold the valve member weight withinreasonable limits so that an undue amount of lift will not be requiredto open it, I prefer to feed the water system from an elevated tank bygravity. A pressure system may be employed, however, if circumstancesdictate such use, by proper .design of the valve, or by use of a valveof difierent type.

With regard to the tank drain valve 39,*the important considerationhere'is that the valve disc have enough area so that the static headacting upon its upper side will produce a force Having describedapreierred iorm of my -invention and having pointed out the principalconsiderations to be observed in the construction of equivalent systems,it is understood that the invention is to be limited only in accordancewith the scope of the appended'clalms." While my invention isparticularly useful tor determining and I claim:

1. In a device for obtaining a continuous record of drilling-muddensity, the combination com.- prised or a tank wherein a sample of mudis accumulated, displacement means within said tank for measuring thedensity of the sample, means associated with said displacement means forrecording said density, a weight-loaded beam associated with said tank,a second tank suspended irom said beam and positioned to catch anoverflow oi fluid from the first said tank, and valve means operativelyconnected to said beam to control the admission of mud to the first saidtank.

2. In a weighing device for fluid material substantially as described,the apparatus comprising a tank wherein the density of a fluid sample isto be determinedwalve means controlling admission and removal of 'saidfluid sample, weightactuated means operable by'overflowed iiuid iromsaid tank to control said valve means, a clean water supply lineincluding a shutoff valve, said shutoflf valve being operable by saidweight-actuated means to admit clean water to said tank before admissionof a succeeding'fluid sample.

3. A mud weighing device comprising incombination a test tank, ahydrometer with displacement means in the test tank: means forperiodically filling with drilling mud and emptying said test tankcomprising filling, emptying and overflow conduits in the test tank,valve means in said filling and emptying conduits, lever means tooperate said valves, and a container filled from said overflow tooperate said lever, whereby said hydrometer will indicate the specificgravity oi the mud when the test tank is full arid cleaning meanscomprising a liquid stream controlled by the motion of said lever andoperating while the test tank is emptying for cleaning any inuddepositfrom the tank, the container and displacement means.

4. A mud weighing device comprising in com-' bination a test tank, ahydrometer with displacement means in the test'tank, means forperiodically filling with drilling mud and emptying said said overflowto operate said lever, said container having a dump valve, whereby saidhydrometer will indicate the specific gravity or the mud when the testtank is full. and cleaning means comprising a liquid stream controlledby the motion 01' said lever and operating while the test tank .isemptying for cleaning any mud deposit "from the tank, the container,dump valve and displace ment means.

- JOHN R. PE'I'I'IGROVE.

